<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            background-color: #ccc;
        }

        .main {
            width: 300px;
            height: 300px;
            margin: auto;
        }

        .main-left {
            width: 150px;
            height: 300px;
            border-radius: 150px 0 0 150px;
            background-color: #fff;
            position: relative;
            float: left;
        }

        .main-right {
            width: 150px;
            height: 300px;
            border-radius: 0 150px 150px 0;
            background-color: #000;
            float: right;
        }

        .black {
            position: absolute;
            top: 0;
            left: 75px;
            width: 150px;
            height: 150px;
            background-color: #000;
            border-radius: 50%;
        }

        .white {
            position: absolute;
            top: 150px;
            left: 75px;
            width: 150px;
            height: 150px;
            background-color: #fff;
            border-radius: 50%;
        }

        .whiteCircle {
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background-color: #fff;
            position: absolute;
            left: 75px;
            top: 75px;
            margin-top: -10px;
            margin-left: -10px;
        }

        .blackCircle {
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background-color: #000;
            position: absolute;
            left: 75px;
            top: 75px;
            margin-top: -10px;
            margin-left: -10px;
        }
    </style>
</head>

<body>
    <div class="main">
        <div class="main-left">
            <div class="white">
                <div class="blackCircle"></div>
            </div>
            <div class="black">
                <div class="whiteCircle"></div>
            </div>
        </div>
        <div class="main-right"></div>
    </div>

</body>

</html>